Fluctuation theorem for a single particle in a moving billiard: experiments and simulations.

A single particle within a periodically driven Sinai-billiard-like system is tracked experimentally and is simulated via hard-sphere molecular dynamics. Both experiments and simulations confirm the fluctuation theorem (FT); thus, in this setup, one driven particle is sufficient for the FT to hold. Furthermore, in the simulations the chaoticity of the system can be adjusted using the restitution coefficient of collisions. It is also shown that the FT breaks down when unstable periodic orbits appear for small restitution coefficients.